DISPLAY FOR ANALOG/DIGITAL VISUALIZING OF COMPUTER STORED AND BITMAP CONTROLLED, IN FORM OF STILL OR MOTION, IMAGES

Abstract: A display for digital/analogous visualization of computer stored and bitmapped, in form of still or moving patterns, e.g. text, image or the like on or by means of at least one visualization medium (8, 8a, 15). The display consists of one matrix (1) including at least two sets of each other crossing electrodes (4, 5, 18, 19), distanced from each other by means of at least one resistive and/or inductive spacer means (2), and connected to at least one control device (6) for multiplexing, scanning or pulsating the control signals. The electrodes are individually addressable in accordance to electic signals from a control unit and provided so that when selected electrodes in both sets of the electrodes are energized, a temperature change is obtained in the crossing point of the conducting electrodes, which temperature change (heat) is conducted towards said medium, which medium includes a thermosensitive indication means (8a), such as a layer, a body or the like. The surface/surfaces in the display (8) are provided to transform the temperature change to visible dots or the like.

Description: DISPLAY FOR ANALOG/DIGITAL VISUALIZING OF COMPUTER STORED AND BITMAP CONTROLLED,INFORMOFSTILLORMOTION,IMAGES The present invention refers to a display for digital/analogous visualization of computer stored and bitmapped, still or moving patterns, eg text, images or the like on or by means of at least one visualization means. BACKGROUND OF THE INVENTION In certain applications, such as price indicators in shops, information indicators at shop windows or the like, advertising signs other fields requiring visualization of information, there is a need for a display means, which can be manufactured in large quantities with low cost. The big problems with the LCD (Liquid Crystal Display) and TFT (Thin Film Transistor) screens are that a large number of displays are discarded due to sensitivity of the manufacturing process. US 3,637,291 discloses a display, in which enclosed floating crystals are used as image carrying medium, which crystals have two optical states, i.e. a first translucent state and another opaque state. The crystal layer becomes translucent first when it is exposed to a momentary electric field, whereas the visible image is created by elevating the temperature in the desired points, which become opaque. This device consists of many parts to be controlled and the control method entails several stages for production of a visible dot. Through US 4,922,242 a visualization means for visualization of premanufactured form is known. The visualization means consists of two electrodes with a resistive layer between them. A thermochromatic layer is provided between a pigment layer and a transparent polymeric layer. The image, such as a digit to be shown, is cut out as a metallic mesh. When an electric current passes through the electrodes, the resistive layer is warmed up. The heat is guided to the thermochromatic layer, which becomes translucent due to the heat, whereas the pigment layer becomes visible. This type of display is not flexible, and must be formed in a predetermined shape and cannot show moving images. THE OBJECT AND MOST IMPORTANT CHARACTERISTICS OF THE INVENTION The object of the present invention is to provide a display for still and moving images, for example consisting of characters and/or patterns, which display can be manufactured simply and with low cost, having few parts, and can be flexible for certain applications, such as winding types. These tasks have been solved by the display consisting of a matrix, including at least two sets of electrodes, crossing each other and distanced from each other by means of at least one resistive and/or inductive spacer means, and connected to at least one control device, for multiplexing, scanning or pulsating the control signals, that the electrodes are individually addressable according to the electric signals from a control unit and arranged so that, when the selected electrodes in both set of the electrodes are energized, a temperature change in the cross-points of the charged electrodes is obtained, and the temperature change (heat) is conducted towards said medium, which includes a thermosensitive indication means, such as a layer, a body or the like, and that said surface/surfaces of the display, is/are provided to transform the temperature change to visible dots or the like. DESCRIPTION OF THE DRAWINGS In the followings the invention will be described by referring to a number of embodiments, and attached drawings. Fig. la in perspective shows a first embodiment of a portion of a visualization means according to the invention, with the visualization medium partly folded. Fig. lb discloses a section along the line A-A in Fig. la. Fig. 2a discloses a perspective view of another embodiment of a portion of a matrix included in the device. Fig. 2b shows a section along the line B-B in Fig. 2a. Fig. 3,4 and 5 show an enlarged section through the electrodes of the matrix having different types, forms and characters. Fig. 5a discloses a perspective view of a part of the upper electrode used in Fig. 5. Fig. 6 shows a perspective view of a design embodiment of the resistive spacers situated between the electrodes. Fig. 7a shows in perspective an additional design variant design of the resistive spacers. Fig. 7b discloses a section along the line C-C in Fig. 7a. Fig. 8a shows in perspective a matrix arranged with transistors. Fig. 8b shows an enlarged view of the transistor of the matrix. Fig. 9a discloses, in perspective view a part of a matrix having translucent electrodes in both sets of the electrodes. Fig. 9b shows a section through a crossing point of the matrix according to Fig. 9a. Fig. 10 shows a view, analogous to Fig. 1, of a modified embodiment. Fig. 11 discloses in an elevated view a part of a matrix with woven design. Fig. 12 shows in perspective the matrix disclosed in fig. 11. Fig. 13 shows in an elevated view another embodiment of a part of a matrix. Fig. 14 discloses, in perspective the marina disclosed in fig. 13. Fig. 15 discloses, in perspective, an electrode matrix for a double-sided display. Fig. 16 shows, in perspective, utilization of the device for shelf marking. Fig. 17 shows an application of a display according to the invention in a portable telephone. DESCRIPTION OF THE EMBODIMENTS The basic idea with the invention is that in individually addressable, limited areas, eg dots, produce temperature changes, preferably temperature increases, which influence a thermosensitive material in a visualization medium, which visualizes the dots according to the desired pattern. In the embodiment shown in fig. la and lb the visualization means consist of a matrix 1, including a resistive spacer means shaped as a plate 2 made of semiconductor material, for a first set of electrodes 4 provided in parallel rows on the one flat side of the plate 2 and another set of electrodes 5, provided likewise in parallel rows, but situated in an angle opposing the first set of the electrodes and placed on the other flat side of the plate 2. The sets of electrodes are consequently provided in X and Y coordinates, but the angles between these do not need to be 90 degrees, but can have other magnitude. All electrodes are connected to control units 6, eg integrated driving circuits, which are so programmed that each electrode in one of these first sets is individually connectable to a voltage source U, while each electrode in the other set is individually connectable to ground. For example, if the electrodes 5b and 5d are connected to the voltage U and the electrode 4b to ground via the resistive plate 2, heat is in the crossing point between said electrodes in the plate, heat is produced within a limited space 7, which is shown by the cylinder on the drawing. The heat is distributed to the heat surface 3 of the matrix 1, while its opposite surface is insulated against the heat by means of an insulation plate 10. The control of the matrix can be arranged by multiplexing the voltage connections. The control voltage to the electrodes can be pulsated, i.e. each selected crossing point, which should show a dot is pulsated with an amount of energy per time unit, so that its indicated heat remains until the screen is updated next time. The pulsating can occur by addressing each point continuously with voltage and/or current pulses, switching on/off the dot by changing the dot address or multiplexing or scanning. Instead of using wire or ribbon shaped electrodes, it is also possible to make the electrodes 4,5 by printing an electric conducting medium, for example silver dye, water/glass or the like. When the visualization means is used as a display or the like a visualization medium 8 is placed in a heat conducting contact against this, which partly comprises of a temperature sensitive < indication layer 8a, which is so constituted that it transforms the plumped heat to a visible dot 9, for example as a colour change, and partly a heat receiving surface 8b. It is also possible to show the visualized pattern in colour, by controlling the voltage to the electrodes, by means of the control unit 6 and thereby the temperature in the crossing points of the electrodes. In this case as a temperature sensitive indication layer 8a a reversible thermo dye is used, which in respect to the temperature assumes different colours. By intermittently energizing the electrodes 4,5 of the matrix 1, information can be visualized during a long time, which makes it possible to use the display, e.g. as product and price information sign on shelves, as shown in fig. 16. The heat conduction causes a delayed turn off, which permits multiplexing through scanning procedure. In a modified embodiment of the invention according to fig. 2a and 2b the semiconductor plate is replaced by semiconductor pellets 11, possibly provided in a poor heat conducting plate (not shown) whereby a more distinct lumped heat is received by the heat emitting surface 3. As it appears from the figures 3,4 and 5 the electrodes are arranged in different ways, but even their cross-section can have a form adapted for the purpose. Consequently, the electrodes in fig. 3 have round cross-section and one of the electrodes 4 of the set of the electrodes is placed inside the pellet 11 and the plate 2, respectively. From fig. 4 appears that the plate 2 or the pellets 11 can be divided in two parts, whereas in one lower part, the electrode 4 is inserted and the part consists of a semiconductor material, while the upper part 12 forms a good heat conductor, which transports the heat to the visualization medium 8. If needed, the electrodes can also be given a certain form, as the one shown in fig. 4. Fig. 6 shows an embodiment, in which the resistive spacer 11 extends over several electrodes 4a - 4d in a set of electrodes. In Fig.7a and 7b the resistive spacer 2 has a strong radial area reduction 13, which causes a notable increase of resistance, which in turn results in heat generation in this part. The lumped heating of the matrix 1 can also be achieved by providing it with transistors 16, in accordance with the embodiment disclosed in Fig. 8, where 17 refers to the base of the transistor, 18 the emitter, 19 the collector and 20 the resistor. In this case, the transistors are used first as local heat sources, which emit their heat to the heat emitting surface 3 of the matrix, consisting of several cone or pyramid shaped elevations for each transistor. In the embodiment according to Fig.9a the visualization medium 8 is integrated in the plate shaped resistant spacer 2, which means that the temperature sensitive, reversible indication material 8a, can be micro encapsulated floating crystals, are by means of a binding agent, such as a semiconducting plastic material, are integrated into a plate 2, against which the electrodes 4,5 bear on. To be able to see the visible heat dots through the electrodes, they must be transparent, eg made of in entine oxide (In 2 0 3 [Sn0 2 ] ). The resistive or heat producing layer 2, for example can consist of DAP (Diallyl Phthalate, COSMIC PLASTIC INC., USA). The layer 2 can also consist of a transparent thermoplastic material, being used in precision potentiometers. The material is applied, eg through "screen printing". It is also possible to adjust different resistance values (ohm/cm). The layer can also be made of semiconductor resistive plastic, produced of conducting pigment, eg MICA-PIGMENT (MERK Gmbh) or carbon pigment (carbon black or ketjen black from AKZO, NL). Even polyanelin dipped plastics, so-called PANI, in which the molecule chain forms conducting groups (NESTE OY, FI) can be used in the layer 2. A pigment, dye or foil layer can be used for visualization objects. If the visualization medium 8 changes its optical characteristics (becomes translucent) due to the heat, a pigment layer can be provided below the visualization medium for visibility purposed. The dye layer, for example can consist of fluorescent yellow, luminous material or glass beads (3M). The thermoindicating layer, at room temperature, can be provided with black, opaque layer, preferably based on pigments of micro encapsulated floating crystals. When temperature increases above a preselected temperature for the pigment, the layers transit to transparent, whereas the underlying layer, which can consist of strong luminous colour becomes visible. LCD-pigment normally does not transit from black to transparent. It is normal to start from a shade, which due to increased heat becomes transparent. Thus a black or dark background layer can be provided. To create black LCD-pigment at room temperature, one can through known methods mix different shades, so that their emission wavelengths interfere each other and become black (full absorption). As the surface layer, a thin layer of some transparent ultraviolet absorber can be used to protect the underlying layer. For certain applications the embodiment according to Fig. 9b can be applicable, in accordance to which a temperature sensitive indication material 8a, eg stearin, is used in the bores of the resistant disc 2, which indication material due to the heat becomes transparent. The visualization is obtained by means of a light source 14 placed behind the matrix, which illuminates through the softened stearin. In this case, even the electrodes 4,5 must consist a transparent material. One can also show light dots in firm colours by illuminating a background colour or give the illumination a certain colour, which is transmitted through the heated transparent dots. According to a preferred embodiment, shown in fig. 10, the matrix 1 consist of a double-sided circuit board or film, where the board/carrier consist of a semiconductor material 2 and the electrodes on both sides of the board/carrier of the printed circuit board type. The temperature sensitive indication material 8a is arranged in the visualization medium 8, which may be integrated within the matrix 1. An additional embodiment is shown in figs. 11 and 12, where the matrix 1 consists of a web, wires of which are conducting and surrounded by a semiconductor coating 22. The wires form the electrodes 4,5 of the matrix, whereby the electrodes in one set of the electrodes are provided in the weft direction of the web and the electrodes in the other set of the electrodes are in the weft direction of the web. The resistive spacers 2 consists of the semiconductor coating 22. With this embodiment is possible to produce matrices in a simple and cheap way with very high resolution if thin wires, i.e. electrodes are chosen. Fig. 15 discloses schematically a section through an embodiment consisting of three electrode layers 4, 5 and 23. By using such an embodiment the display can be used for double-sided vis¬ ualization of information. Between the electrode layers 4 and 5; 5 and 23, the resistive layer 2 and on the electrodes, the visualization medium 8 are arranged. To avoid the information at visualization to become reversed on the opposite side of the display, the electrodes are connected according to fig. 15a, where each electrode 4, for example from right to left on one side of the display is connected to same control voltage as the electrodes 23 on the other side of the display, but from left to right. If translucent electrodes are used, one surface of the electrodes 5 or the heat generating layer can be covered by a colour or pigment layer 24. To reduce the heat distribution through the matrix conductors 4 and 5, increase the contrast and extension of the hot dots the matrix can be formed according to the embodiment shown in figs. 13 and 14. The matrix is made of very thin conductors connected to the connection plates 21. Fig. 17 shows a second application of a display unit according to the invention. The display 24 in this case consists of thin and flexible electrodes, for example of semiconductor plastic or metallic stripes. Also the visualization medium and the resistive, heat generating layer are of some flexible material, which enables the winding up 27 the display, for example inside a mobile telephone 26. The display according to this embodiment can be used to receive long messages, drawings or the like. When a message package is read, the display is winded out. For example a mobile telephone is provided with a facsimile receiver/transmitter, if a message with drawings/text is sent to the user of the portable/mobile telephone, the user can roll out the screen, read the message and store it on a thermopaper by pressing the paper against the screen. Fig. 17a shows a section through the telephone 26 according to fig. 17 with a part of the display winded up 27 inside the telephone. The visualization does not have to be achieved only through heat¬ ing of the dots. The entire display surface can be warmed up and the indication can occur through switching off (coldness) the areas to be visualized. The screen can also be provided with base heating, i.e. the dots are warmed up to a certain threshold level, which causes faster "lighting" of the dots and thereby lesser energy and time consumption. During longer operation periods the screen may be heated. The problem can be solved by using an efficient cooling, or by decreasing the amount of the supplied energy by measuring and adjusting the temperature. The temperature measurement can be provided through a special sensor unit or measurement of resistance alterations in the heat generating layer. The invention is not limited to the above described embodiments and other embodiments within the scoop of the claims can be provided.

Claims: CLAIM 1. A display for digital/analogous visualization of computer stored and bitmapped, in form of still or moving patterns, eg text, image or the like on or by means of at least one visualization medium (8, 8a, 15), characterised in, that the display consists of a matrix (1) including at least two sets of electrodes (4,5,18,19) crossing each other, spaced from each other by means of at least one resistive and/or inductive spacer means (2), and connected to at least one control device (6), for multiplexing, scanning or pulsating the control signals, that the electrodes are individually addressable in accordance with electric signals from a control unit and so provided that when selected, the electrodes in both set of the electrodes are energized, and a temperature change is obtained in the crossing points of the electrodes, which temperature change (heat) is conducted against said medium, which includes a thermosensitive indication means (8a), such as a layer, a body or the like, and that said surface/surfaces in the display (8), is/are provided to transform the temperature change to visible dots or the like. 2. A display according to claim 1, characterised in, that the resistive spacer (2; 11) between the electrodes (4,5) in both set of the electrodes consist of electric resistive material, semiconductor material or area reduction (13) of a conducting member (23) between the electrodes. 3. A display according to claim 1, characterised in, that the resistive spacer (2, 11) is divided in a first resistive part (11) and a second part (12) having good heat conducting characteristics, and that the electrodes (4) in one set of the electrodes are placed in a space between both parts (11,12). 4. A display according to claim 1, characterised in, 5 that the resistive spacer (2,11) has an extension over several electrodes in the set of the electrodes. 5. A display according to claim 1, characterised in, 10 that the electrodes (4) in one set of the electrodes are arranged essentially parallel and displaced in an angle relative, in the same way essentially parallel electrodes (5) in the other set of the electrodes. 15 6. A display according to claim 1, characterised in, that the electrodes (4,5) are inserted or embedded in the resistive spacer (2). 20 7. A display according to claim 1, characterised in, that the electrodes are transparent, eg produced of injentin oxi¬ de (In 2 0 3 [Sno 2 ] ). 8. A display according to claim 1, 25 characterised in, that the electrodes (4,5) are produced by applying, eg printing, an electric conducting medium, eg silver dye, water glass or the like on the resistive spacer means (2) of the matrix. 30 9. A display according to claim 1, characterised in, that each electrode (4, 5) in one set of the electrodes consists of an emitter arranged in a base and each electrode in the other set of the electrodes of a collector. 35. 10. A display according to claim 1, characterised in, that said thermosensitive means (8a) consists of micro en¬ capsulated floating crystals or the like. 11. A display according to claim 1, characterised in, that the visualization medium (8) consists of reversible temperature indicators. 12. A display according to claim 1, characterised in, that the visualization medium (8) includes thermosensitive indication layer consisting of crystalline plastic, crystalline wax or the like, provided transparent at glassing temperature. 13. A display according to claim 1, characterised in, that the thermosensitive indication material of the visualization medium (8) constitute an integrated part of the resistive spacer (2), whereby the indication materially, consists of micro encapsulated floating crystals embedded with a binding agent of semiconductor plastic. 14. A display according to claim 1, characterised in, that the temperature sensitive indication layer (8a) of the visualization medium (8) is formed to change colour at least within a part of the colour spectral at temperature changes, and that the control unit (6) is provided to control the voltage to the electrodes (4,5) due to the temperature, at which a certain desired colour change of the temperature sensitive indication layer (8a) occurs. 15. A display according to claim 1, characterised in, that the indication layer (8a), which at heating stage are transparent and thermosensitive are illuminated, possibly by means of coloured illumination or by means of illuminated background colour, so that the light is transmitted through the indication layer. 16. A display according to claim 1, characterised in, that the matrix (1) consists of a web of electric conductors, which are surrounded by a semiconductor coating, whereby the electrodes in one set of the electrodes are arranged in warp direction of the wed and the electrodes in the other set of the electrode in the weft direction of the wed. 17. A display according to any of previous claims, characterised in, that the heat generating layer (2) is transparent thermoplastic material. 18. A display according to claim 17, characterised in, that the heat generating layer (2) consists of DIALLYL PHTHALATE. 19. A display according to claim 17, characterised in, that the heat generating layer (2) is applied by screen printing, and/or that the layer is adjustable to different resistance values (ohm/cm). 20. A display according to claim 1, characterised in, that the electrodes (4, 5, 22), the heat generating layer (2) and the visualization medium (8), consist of thin, elastic material, for example in form of a roller blind, foldable surface, in particular for usage in mobile telephones. 21. A display according to claim 1, characterised in, that the control voltage to the electrodes is arranged periodically with amount of energy per time unit, so that the indicated heat is remained until next update of the display. 22. A display according to claim 1, characterised in, that the display is double-sided.

Inventors: LARSON OVE, LARSON, OVE
Applicants: LARSON OVE, LARSON, OVE
Application year: 1994
Main classification: B41J2
IPC codes: G01J5, G02F1, G09F9, G09G3